Municipal Solid Waste Research Articles

Taxonomic and functional profiling of microbial community in municipal solid waste dumpsite

Taxonomic and functional profiling of microbial community in municipal solid waste dumpsite

Characterization of Long‐Term Municipal Solid Waste Constitutive Behavior With Coupled Biodegradation and Fibrous Reinforcing Effects

ABSTRACTTo appropriately simulate the long‐term mechanical behavior of municipal solid waste (MSW), a constitutive model coupling the effects of biodegradation and fibrous reinforcement was developed. In the proposed model, the compressive deformation due to biodegradation was regarded as being caused by an additional equivalent stress. Considering the effect of biodegradation, an evolution equation of the equivalent stress was proposed, and a plastic volumetric strain hardening law was developed. A fibrous reinforcement parameter was introduced, which was associated with the fiber content, stress state, and plastic shear strain of MSW. A plastic shear strain hardening law was developed to model the fibrous reinforcement. Based on the associated flow rule and two plastic strain hardening laws, the proposed model was established. The proposed model well simulated the hardening properties of MSW, as evidenced by the stress‒strain curves and the consistent, nonlinear increase in volumetric strain with axial strain. The differences in the shear strength and volumetric deformation due to the confining stress and fiber content were also well simulated by the model. Furthermore, the model predictions accurately reflected the findings of experiments conducted over a period of 10 years. Finally, parametric investigations were used to calibrate this proposed model, which can well characterize the long‐term MSW mechanical behavior.

Organic waste and beechwood cellulose blend saccharification and validation of hydrolysates by fermentation.

This study demonstrates the sustainable advancement of fermentation media by blending the organic fraction of municipal solid waste (OFMSW) with organosolv beechwood cellulose. Investigations examined the effects of enzyme dosages and OFMSW integration into organosolv beechwood cellulose on sugar yield. The findings indicate that OFMSW inclusion and Cellic® CTec3 dosage significantly influence hydrolysis across two different batches of beechwood cellulose. Experimental data showed that OFMSW inclusion levels of 35% and 45% (w/w) produced sugar levels comparable to pure beechwood cellulose, achieving 58% to 68% (w/w) saccharification with sugar concentrations of 44 to 46g/L. This highlights OFMSW's potential as a buffer substitute during the enzymatic conversion of organosolv cellulose. The resulting sugar-rich hydrolysates, derived from OFMSW-cellulose blends and pure cellulose, were evaluated for ethanol and cell biomass production using Saccharomyces cerevisiae and Mucor indicus, yielding 30g of ethanol/L hydrolysate. Furthermore, OFMSW inclusion in beechwood cellulose proved to be an excellent alternative to synthetic nitrogen agents for S. cerevisiae cell production, reaching 12.2g of biomass/L and surpassing the biomass concentration from cultivation on cellulose hydrolysate with nitrogen supplementation by threefold. However, M. indicus did not grow in the OFMSW-cellulose blend, suggesting that the inhibitory compounds of OFMSW may be a bottleneck in the proposed process. The present study demonstrates the benefits of incorporating OFMSW into cellulose material, as it enhances both cost-effectiveness and sustainability. This is attributed to the natural buffering properties and nitrogen content of OFMSW, which reduces the need for synthetic agents in fermentation-based lignocellulose biorefineries. KEY POINTS: • OFMSW inclusion significantly influences beechwood cellulose saccharification. • OFMSW could be an excellent alternative for synthetic agents in biorefinery. • S. cerevisiae achieved higher biomass growth on OFMSW/cellulose mix compared to YPD.

Study of municipal solid waste treatment using plasma gasification by application of Aspen Plus

Abstract Plasma gasification is a viable and efficient technique for handling solid waste, including hazardous waste, while also holding the potential for energy recovery. The objective of this study is to analyze the treatment of municipal solid waste (MSW) using plasma gasification by application of Aspen Plus software. An earlier proposed model was used to analyze the effect of employing different types of gasifying agents as plasma gas, on the composition of syngas produced. The lower heating value, cold gasification efficiency and carbon conversion efficiency were calculated and compared in each case. A sensitivity analysis study was also carried out to observe the effect of variation in plasma gas flow rate and feed flow rate on the composition of syngas generated. The capital, operational and maintenance costs of the process were determined using existing correlations. For a feed rate of 20,000 kg per hour of MSW, the highest yield of syngas (CO (33.48 %), and H2 (34.30 %) with the highest LHV (7.9 MJ/N-m3)) were produced when air was employed as plasma gas. The cold gas efficiency and the carbon conversion efficiency were at their peak when air was used as the gasifying agent. The sensitivity analysis revealed that as the flow rate of plasma gas increases syngas production decreases while the increase in MSW flow rate results in an increase in syngas production. Additionally, the cost analysis revealed that for a plasma gasification plant that can handle 500 tons of MSW per day, the estimated capital and annual operational and maintenance costs are $125,496,721 and $9,833,892 respectively.

Feedstock recycling of polycarbonate waste via thermochemical conversion supported by municipal solid waste incinerator bottom ash.

The rising demand for plastics has driven up its production, causing severe environmental challenges like CO2 emissions and microplastic pollution. Furthermore, improper disposal of incinerator bottom ash (IBA), a byproduct of municipal solid waste (MSW) treatment, poses additional environmental risks. This study explores a method for recovering non-petroleum-based monomers from plastic products. A smartphone case waste (SCW) is used as feedstock in this study and it is made of polycarbonate (PC), confirmed by thermogravimetric analysis and Fourier transform infrared spectroscopy. The MSW incinerator bottom ash (MSW-IBA) is used as a catalyst for thermochemical conversion of SCW. To determine the optimal pyrolysis conditions for BPA recovery, experiments were conducted under different atmosphere (N₂ and CO₂) and catalyst configurations (in situ and ex situ). The MSW-IBA leads to 127% higher yield of bisphenol A (BPA), the monomer of PC, at 600 °C under a N2 atmosphere, compared to non-catalytic conversion. In situ configuration of the catalyst loading leads to up to 147% higher BPA yield than ex situ configuration. The increased BPA production from SCW is most likely because metal oxides (e.g., CaO) present on the MSW-IBA catalyst promotes the cleavage of and C-O bonds, dissociation of CO (or CO2) and hydrogen extraction from C1-C3 hydrocarbon and H2. For the catalytic conversion of SCW under a CO2 atmosphere, CO2 adsorbs onto CaO in the MSW-IBA, decreasing the number of active sites. It deactivates the catalyst, resulting in a lower BPA yield (22.96 wt%) than the BPA yield obtained under the N2 atmosphere (25.86 wt%).

Simplified mathematical model of oxy-fuel combustion of municipal solid waste in the grate furnace: effect of different flue gas recirculation rates and comparison with conventional mode

Bioenergy carbon capture technology (BioCCS or BECCS) plays a key role in the European Green Deal, which aims to decarbonize industry and energy sectors, resulting in the production of energy with negative CO2 emissions. Due to the biogenic origin of carbon contained in municipal solid waste (MSW), the application of carbon capture in waste incinera-tion plants can be classified as BioCCS. Thus, this technology has attracted scientists' attention recently since it reduces excessive waste and emissions of carbon dioxide. Currently, there are four incineration plants in the Netherlands, Norway and Japan, in which CO2 capture is implemented; however, they are based on the post-combustion technique since it is the most mature method and not requires many changes in the system. Nevertheless, the separation of CO2 from the flue gas flow, which contains mostly nitrogen, is complex and causes a large drop in the total performance of the system. Oxy-fuel combustion technology involves the replacement of air as an oxidizer into high purity oxygen and recirculated exhaust gas. As a result, CO2-rich gas is produced that is practically ready for capture. The main goal of the study is to develop a math-ematical model of oxy-waste combustion to answer the research questions, such as how the composition of oxidant that is supplied to the process affects the combustion performance. The model includes all important processes taking place within the chamber, such as pyrolysis, char burnout and gas combustion over the grate. The results of the work will contribute to the development of oxy-waste incineration plants and will be useful for design purposes.

Prevalence of occupational injuries and associated factors among solid waste collectors in Jigjiga city, eastern Ethiopia: a cross-sectional study design

BackgroundSolid waste collectors play an important role in maintaining health and hygiene in cities globally. The risk levels are very high in low-income countries since solid waste collectors have low socio-economic status and are exposed directly, unknowingly, and without adequate personal protection to municipal solid waste that contains hazardous materials. Solid waste collectors in Ethiopia are at high risk of occupational injuries due to the manual collection of hazardous solid waste by hand. In Jigjiga city, so far, there has been no study or published research showing the prevalence of occupational injuries and associated factors among municipal solid waste collectors.ObjectiveTo assess the prevalence of occupational injuries and associated factors among solid waste collectors in Jigjiga City, Somali Regional State, Ethiopia, 2023.MethodsAn institutional cross-sectional study was conducted in Jigjiga City, Somali Regional State, involving 247 solid waste collectors. Data was collected through an observational and structured questionnaire and analyzed using Epi Info and STATA software programs. The study used systematic random sampling techniques and bivariate and multivariable logistic regression analyses to determine the statistical association between the outcome variable and independent variables. The significance of the association was tested using the 95% confidence interval and p value (<0.05).ResultsThe overall prevalence of occupational injuries was 54.7% (95% CI: 48.2%, 60.6%). Training on health and safety measures before employment [AOR: 0.43, 95% CI (0.24, 0.80)], sleeping problems [AOR: 3.28, 95% CI (1.86, 5.78)] and Temporary workers [AOR: 2.14, 95% CI (1.16, 3.95)] were significantly associated with occupational injuries.ConclusionThe prevalence rate of occupational injuries among solid waste collectors in Jigjiga City was high. There should be preventive measures, like giving Training on Health and safety before employment, to safeguard the health and safety conditions of the workers.

Variation in the Composition of Municipal Solid Waste Incineration Ash

Unlike municipal solid waste bottom ash (MSWBA), fly ash (MSWFA) is landfilled due to its toxicity. However, MSWFA may also be a source of elements. Ash samples collected from a Portuguese MSW incinerator from different locations and over six months were analyzed. Their geochemical composition was normalized to the upper continental crust (UCC) and compared since metal enrichment may be used as an indicator for potential recovery. The potential recovery economic viability was also assessed for metals K, Sb, Cu, Pb, and Zn, considering the ore cut-off grade and minimum industrial grade (MIG) from Chinese geological and mineral industry standards. Compared to the global samples, only the Baghouse 1 FA size fraction’s coarse fraction showed a slight enrichment (1- to 5-fold) in Bi, Nb, and Zr. After wet sieving, most trace elements were enriched in all fractions, but Sb, Bi, Pb, Zn, Ag, As, Cd, Sn, Se, and Hg were depleted in the coarse fractions and enriched in the fine ones. For Baghouse 1 samples collected over 6 months, the normalization to the UCC showed enrichment of Zn and Pb between 10× and 50×, Zr, Cu, In, and Se between 50× and 100×, and Ag, Mn, Cd, Sb, and Bi at more than 100×. Over six months, the Baghouse 1 FA soluble fraction ranged between 21 wt.% and 30 wt.%, and its precipitates comprised 27% CaO, 6% Na2O, and 9% K2O. The K concentration in the MSWFA was above the cut-off and the MIG, and K could be concentrated in precipitates via simple washing.

Unravelling the detoxification trail of potential toxic heavy metals: an insight into heavy metal auditing and ecological health upon valorisation by Lampito mauritii and Eudrilus eugeniae.

Evidence on prospective remediation of municipal solid waste contaminated with toxic heavy metals by Eudrilus eugeniae (Eu) and Lampito mauritii (L) is very scarce and yet to be explored. In this study, heavy metal detoxification potential of E. eugeniae and L. mauritii in municipal solid waste (MSW) + cowdung (CD) (3:1)-based feedstocks were investigated against Eisenia fetida (E) (a well-known vermi-remediator) and aerobic composting. Excellent reduction (70.01-93.04%) of potentially toxic heavy metals (PTHMs) (Pb, Cr, Cd and Zn) were evident in both E. eugeniae and L. mauritii employed treatments. Moreover, the results on heavy metal budget quotient clearly demonstrated the unique detoxification route undertaken by E. eugeniae and L. mauritii via humic composite facilitated chelation over the nominal bioaccumulation pathway. The principal component analysis (PCA) confirmed the strong negative correlation between the heavy metal (HM) level in earthworm gut and MSW substrate, whereas a strong positive correlation between humic substances and HM remediation. Furthermore, analysis of ecological health parameters indicated substantial reduction of environmental risk and guaranteed negligible risk of PTHM if utilized as manure. Moreover, significant increment in total N content (3.2-3.8-fold), available P (4-5.9-fold), exchangeable K (3.66-fourfold) and enzyme activity along with significant reduction of TOC (~ 87%) confirmed E. eugeniae and L. mauritii could effectively stabilize MSW. Thus, the metal-binding potential of humic substances produced by earthworms during the detoxification of municipal solid waste (MSW), coupled with a metal budget analysis, has offered valuable insights into the usage of E. eugeniae and L. mauritii as effective contenders for sanitizing heavy metal-laden MSW.

Comparative Life Cycle Assessment of Landfilling with Sustainable Waste Management Methods for Municipal Solid Wastes

Municipal solid waste (MSW) generation continues to increase exponentially, leading to the need for better disposal methods. Approximately 50% of the MSW is landfilled in the United States (US). Landfilling is known for its negative effects on the environment and human health. The objective of this study was to conduct a life cycle assessment (LCA) of some of the most common waste treatment methods and propose an alternative and environmentally friendly integrated waste management method (IWM). The LCA was conducted using OpenLCA. Replacing landfilling, incineration, and composting with recycling, gasification, and anaerobic digestion (IWM) reduced the global warming potential from 899 kg CO2 eq to −14.6 kg CO2 eq. The same trend was observed for acidification (from 0.21 kg SO2 eq to −1.1 kg SO2 eq), ecotoxicity (from 2363.8 CTUe to 1.22 CTUe), eutrophication (from 0.5 kg N eq to 0.3 kg N eq), smog formation (from 4.4 kg O3 eq to 1.85 kg O3 eq), ozone depletion (from 2.1 × 10−5 kg CFC-11 eq to 0 kg CFC-11 eq), respiratory effects (from 2.8 × 10−3 kg PM2.5 eq to −7.25 × 10−3 kg PM2.5 eq), cancer (from 2 × 10−5 CTUh to 1.2 × 10−7 CTUh), and non-cancer effects (from 6 × 10−5 to 1.4 × 10−5 CTUh). The results show that an integrated waste management approach with recycling, gasification, and anaerobic digestion can dramatically reduce the environmental and health impacts of municipal solid waste disposal. Policy reforms, technical innovation, economic investment, and social engagement are needed to change waste management paradigm.

Geospatial Analysis of Malaria and Typhoid Prevalence Due to Waste Dumpsite Exposure in Kinshasa Districts with and without Waste Services: A Case Study of Bandalungwa and Bumbu, Democratic Republic of Congo

Municipal solid waste (MSW) management poses substantial challenges in rapidly urbanizing areas, with implications for both the environment and public health. This study focuses on the city of Kinshasa in the Democratic Republic of Congo, investigating whether the presence or absence of solid waste collection services results in varying health and economic impacts, and additionally, seeking to establish a correlation between residing in proximity to dumpsites and the prevalence of diseases like malaria and typhoid, thereby providing a comprehensive understanding of the health implications tied to waste exposure. Health data were collected through survey questionnaires, and the geospatial distribution of 19 dumpsites was analyzed using Google Earth Pro 7.3.1 for satellite imagery and GIS software 10.3.1 to map dumpsites and define 1 km buffer zones around the largest dumpsites for household sampling. Statistical analyses were conducted using R Version 4.2.3, employing Chi-square tests for disease prevalence and logistic regression to assess associations between waste management practices and health outcomes. A multivariate regression was used to evaluate correlations between discomfort symptoms (e.g., nasal and eye irritation) and waste activities. The geospatial analysis revealed significant variation in dumpsite size and location, with larger dumpsites near water bodies and flood-prone areas. The study contributes valuable insights into waste-related health risks, emphasizing the need for improved waste management policies in rapidly urbanizing areas like Kinshasa. The socio-demographic analysis reveals distinct traits within the surveyed populations of two communes, Bandalungwa (Bandal) and Bumbu. Bumbu, characterized by larger open dumpsites and limited waste collection services, exhibits a higher prevalence of certain diseases, particularly typhoid fever, and malaria. This discrepancy is statistically significant (p < 2.2 × 10−16), suggesting a potential link between waste exposure and disease prevalence. In Bandal, self-waste collection is a high risk of exposure to typhoid (OR = 4.834 and p = 0.00001), but the implementation of a waste collection service shows protective effect (OR = 0.206 and p = 0.00001). The lack of waste collection services in Bumbu increases the risk of exposure, although not significantly (OR = 2.268 and p = 0.08). Key findings indicate that waste disposal methods significantly differ between Bandal and Bumbu. Bumbu’s reliance on burning and dumping creates environments conducive to disease vectors, contributing to elevated disease transmission risks. However, an in-depth correlation analysis reveals that specific waste management practices, such as burning, burying, and open dumping, do not exhibit statistically significant associations with disease prevalence, underlining the complexity of disease dynamics. This study contributes valuable insights into the importance for urban public health, particularly in rapidly urbanizing cities like Kinshasa, where inadequate waste management exacerbates health risks. By investigating the correlation between proximity to unregulated dumpsites and the prevalence of diseases such as malaria and typhoid fever, the research underscores the urgent need for targeted waste management policies. The stark health disparities between Bandal, with better waste services, and Bumbu, where services are lacking, highlight the protective effect of organized waste collection. These findings suggest that expanding public waste services and enforcing stricter regulations on waste disposal could reduce disease prevalence in vulnerable areas. Additionally, the study supports integrating waste management into urban planning as a critical public health measure. Its evidence-based approach offers valuable insights for policymakers in Kinshasa and other cities facing similar challenges, emphasizing the broader health implications of environmental governance in urban settings.

Energy recovery from landfill gas in Egypt

AbstractIn developing countries, the transition from dumpsites to landfills is particularly important for addressing the challenges of waste management and promoting sustainable development. The goal of this study is to determine the quantity of gas emissions from landfills in Egypt using LandGEM, Afvalzorg, and Mexico models, as well as analyze the financial benefits and greenhouse gas reductions of producing electricity from municipal solid waste, considering seven different landfills across Egypt. A financial assessment was conducted using the entire lifecycle cost, levelized cost of energy, net present value, internal rate of return, and payback period. While the environmental assessment adopted a methodology to determine greenhouse gas production and reductions due to landfill gas valorization, in a span of 30 years, greenhouse gas emissions are expected to be reduced by 81% following landfill gas utilization based on a 75% gas collection efficiency. Furthermore, the potential electricity generation reaches 358 gigawatt-hours, with plant capacities ranging between 3 and 40 megawatts. The positive net present values obtained demonstrate that landfill gas for electricity generation in Egypt is financially feasible for big landfills. This aims to provide first-hand technical knowledge to waste management stakeholders, including policymakers, planners, decision-makers, and investors, to guide waste management planning and promote financially feasible investment in landfill gas to energy in Egypt. Graphical Abstract

From Trash to Treasure: Assessing the Effectiveness of the Green@Community Recycling Network in Hong Kong

Municipal solid waste (MSW) is a growing problem worldwide posing a variety of environmental and human health impacts. Despite recycling being one major strategy to alleviate MSW production, the effectiveness of recycling has been equivocally dependent on local policy implementation and citizen environmental behavior. To enhance recycling effectiveness in Hong Kong, the government has established Green@Community, a unified community-based network for recycling and public environmental education. Since its establishment, the number of visitors to and the amount of recyclable materials collected at the network increased steadily over time. Our study is the very first to investigate the effectiveness of this territory-wide recycling network. Through a questionnaire survey, we found that respondents’ recycling traits were stronger if they have accrued gift tokens through participating in recycling activities. Visiting a Green@Community facility could also enhance knowledge of the types of acceptable recyclables, and respondents who had visited a Green@Community facility agreed that education and publicity could increase the recycling rate in Hong Kong. These findings highlighted the effectiveness and uniqueness of this community-based recycling network, its role in raising recycling knowledge, and its implications for policymakers and urban planners of densely populated cities to leverage society’s recycling participation, but also called for more efforts on developing, promoting, and incentivizing the usage of such a network to further enhance recycling and alleviate MSW production in Hong Kong.

Semi-Aerobic Landfill System as Alternative Solution for Indonesian Landfill

Indonesia has been encountering pressing problems in managing municipal solid waste (MSW). According to data from the Ministry of Environment and Forestry (KLHK), up to 35.46% of landfills were run as open-dumping landfills until May 2022 because proper sanitary landfill concepts were not fully implemented and the condition of landfills in Indonesia is on the point of being overcapacity. With the development of landfill technology, the Ministry of Public Works is currently starting to develop other alternative landfill systems. From the general findings of this study, it can be concluded that the semi-aerobic landfill system is an available method to be used as an alternative solution for Indonesian landfills. This is based on the results of the SWOT matrix, which shows strategic factors derived from internal and external factors originating from previous studies and issues regarding landfills in Indonesia. The analysis of these factors shows that the semi-aerobic landfill system produces better performance by reducing the potential for environmental pollution of water and air and greenhouse gas emissions. The implementation of a semi-aerobic landfill system is a viable method to be used in developing countries.

Determination of Particle Size for Optimum Biogas Production from Ouagadougou Municipal Organic Solid Waste

Anaerobic digestion’s contribution to sustainable development is well established. It is a sustainable production process that enables energy to be saved and produced and efficient pollution control processes to be implemented, thereby contributing to the sustainable development of our societies. Optimizing biogas yields from the anaerobic digestion of municipal organic waste is crucial for maximum energy recovery and has become an important topic of interest. Substrate particle size is a key process parameter in biogas production and precedes other pretreatment methods for most organic materials. This study aims to evaluate the impact of particle size and incubation period on biomethane production from municipal solid waste. Sampling of municipal solid waste was carried out in waste pre-collection in the city of Ouagadougou, Burkina Faso. Waste characterization showed lignocellulolytic green waste (grass, dead leaves), waste composed of fruit and leafy vegetables and leftover food waste. TableCurve 3D v4.0 software was used to develop an optimal mathematical model to correlate particle size and biomethane productivity to describe optimal production parameters. Particle sizes ranging from 2000 to 63 µm high biogas production values, specifically 385.33 and 201.25 L·kg−1 of MSV. PCA analysis clearly showed a high correlation between particle size and biogas production, with optimum production recorded for size 250 µm with a biomethane production value of 187.53 L·kg−1 of MSV. The average relative errors and RMSE for CH4 content were improved by 24.31% and 44.97%, respectively. The data calculated with the developed mathematical model and the existing experimental data were compared and permutated to validate the model. This work enabled the identification of a mathematical model that describes the correlations between the input parameters of an experiment and the monitored parameters, as well as the definition of the particle size that allows for the optimal production of biomethane.

Influence of Self-Heating on Landfill Leachate Migration

The hydrodynamic processes of landfill leachate migration in the base of a solid waste landfill can have a critical impact on the natural environment. In the case of improper operation of municipal solid waste placement facilities, highly contaminated leachate may penetrate into groundwater and subsequently into surface water. This work addresses fundamental issues of multicomponent fluid propagation in a multilayer porous medium, taking into account temperature inhomogeneities caused by waste decomposition with heat release. The regimes of diffusion and convection of leachate water penetrating into soil layers in the base of municipal solid waste facilities are numerically studied. Archival data from a set of field and laboratory measurements in the area of the operating landfill are used to model the features of pollutant propagation and determine migration parameters. The process of pollutant propagation and migration is described by quantitative values of dry residue content in leachate. Factors that have a significant impact on the migration of leachate are considered. The main ones are convective transfer, diffusion, and properties of the geological composition of the landfill base, which are taken into account in the mathematical formulation of the problem. The calculations show that leachate self-heating can substantially intensify leachate filtration and has to be taken into account in the assessment of leachate migration rate.

Characteristics and pollution indices of leachates from municipal solid waste landfills in Iranian metropolises and their implications for MSW management

Leachate from municipal solid waste landfills poses a significant threat to aquatic ecosystems due to poor management practices. This study evaluated thirty leachate samples from Iranian metropolises using the Leachate Pollution Index (LPI). Various parameters, including BOD₅, COD, TDS, pH, EC, heavy metals, turbidity, PAHs, phthalates, and humic acid, were analysed. The BOD₅ levels ranged from 350 to 20,000 mg/L, and the COD levels ranged from 2,000 to 90,000 mg/L. The TDS content varied between 14.7 and 67 g/L, while the turbidity ranged from 15 to 186 NTU. Heavy metals were present but within standard limits. The phthalate concentrations ranged from 6 to 150.8 mg/L, and the humic acid concentrations ranged from 135 to 2,200 mg/L. Naphthalene was the most frequent hydrocarbon detected. The LPIs were less than 30 for all the samples, with the highest in Ahvaz and the lowest in the treated samples from Tehran. This study highlights the presence of persistent organic and hazardous contaminants in Iran’s municipal landfills, emphasizing the need for effective leachate treatment and improved waste management practices. Enhanced final disposal methods, increased waste recovery, and improved solid residue separation are crucial for preventing further leachate production and environmental contamination.

Governance of rural solid waste under a multi-subject governance model

Rural solid waste (RSW) exhibits distinct characteristics compared to municipal solid waste (MSW), such as dispersed distribution, long governance chains, and low recycling value, making it unsuitable to apply the same management measures as MSW. Government-led RSW management results in excessive administrative costs, and the inherent characteristics of RSW reduce market enthusiasm for its management. To address these issues, this paper integrates the “ multi-subject governance “ model with RSW management and establishes a systematic evaluation index system for RSW governance. Utilizing the Best-Worst Method (BWM), key factors were identified. Utilizing the VIKOR method, representative provinces in China were used as case studies to validate the scientific nature of the evaluation indices. The research findings indicate that the multi-subject governance model is an effective approach for RSW management. Key factors influencing RSW management effectiveness include various governmental measures, waste sorting, and a long-term multi-subject governance mechanism. Case analysis reveals a strong correlation between the level of economic development and the effectiveness of RSW management. However, constructing a government-led, multi-subject collaborative urban-rural interconnected RSW management model can effectively address RSW management issues in economically underdeveloped areas. This research provides innovative solutions for RSW management, contributing to high-quality and sustainable development in rural areas.

Methane Generation Potential of the Easily Degradable Group of Landfilled Municipal Solid Waste

Municipal solid waste (MSW) remains in sanitary landfills for many years. To maintain a circular economy, assessing the feasibility of reinserting MSW excavated from sanitary landfills into the production chain is important. This reduces environmental impacts, helping to minimize soil, water, and air pollution resulting from the decomposition of waste in landfills. In addition, it promotes economic benefits from the energy recovery of waste, such as biomass, which can generate electricity and heat, contributing to a sustainable energy matrix. The present study aimed to evaluate the easily degradable MSW group with 24 years of landfilling (ED-24) regarding its potential for methane generation. The ED group consisted of putrescible organic matter, wood, paper, cardboard, and pruning landfilled at a sanitary landfill in Southeastern Brazil. The feasibility of valuing ED-24 as a substrate for anaerobic digestion was assessed by analyzing its physical, chemical, and biochemical characterization and calculating its theoretical methane yield (TMY). The total volatile solids (TVS) and holo-cellulose contents of ED-24 were 73.45% and 61.39%, respectively, on a dry-weight basis. These values were in the range of those determined for non-landfilled lignocellulosic materials. Thus, 24 years of landfilling partially degraded the anaerobically lignocellulosic materials. The TMY of ED-24 was 233.41 mL CH4/g TVS, indicating a potential to generate methane. Despite the high lignin value, ED-24 can be valued as a substrate for anaerobic digestion.

Life cycle sustainability assessment of microbial oil from organic waste

Microbial oils (MOs) are lipids produced by oleaginous microorganisms, which constitute an alternative to vegetable and fossil-derived oils. They can be produced from organic waste by coupling acidogenic fermentation (AF) with oleaginous fermentation (OF). This study addresses a life cycle sustainability assessment (LCSA) of MO produced from the organic fraction of municipal solid waste. First, a system was modelled using simulation tools. This model combines AF for the production of volatile fatty acids from organic waste, OF for the production of lipid-rich yeasts, and MO extraction. LCSA results indicate the need for improvements in the disruption of yeasts and the overall efficiency of the system. Particularly, slightly acidified thermolysis turned out to involve excessively high steam requirements. An enhanced sustainability performance could be achieved by exploring alternative disruption methods or alternative sources of energy for the production of steam such as biogas from the valorisation of the sludges produced in the system.